Answer:
January 24, 2021 (write off)
Dr Allowance for Doubtful Accounts account 7,200
Cr Accounts Receivable account 7,200
March 4, 2021 (write off reversing)
Dr Accounts Receivable account 7.200
Cr Allowance for Doubtful Accounts account 7,200
March 4, 2021 (record collection)
Dr Cash account 7,200
Cr Accounts Receivable account 7,200